Method and apparatus for desurfacing ferrous metal bodies



y 9, 1939. J. H. BUCKNAM 2,157,095

METHOD AND APPARATUS FOR DESURFACING FERROUS METAL BODIES 7 Filed Oct.24, 1936 INVENTOR ORNEYS Patented May 9, 1 93 9 STATES METHOD ANDAPPARATUS Fon'DEsUrtFAcunoramtous METAL ooms e James Harold Bucknam,Cranford, N.,J.I. assignor 3 I to. The Linde Products company 'New'ffyork, N-j a corporation of ohm v I I .-Application:.0ctober 24, 193Serial No.1 I

Claims. (menses), I

. This invention relates to a method and apparatus fordesurfacingferrous metal bodies, and more particularly, to 'a method andapparatus for conserving the shape and heat of the relatively 1teristics and efiectsare had.

A specificobject ofthe invention is toprovide' a procedurefor'assistingthe surface tension-of the reaction puddle to act in amanner tending to a reaction puddlei'ntact'in a central position withlarge reaction puddle which is formed thermochemically when desurfacingwith a gang of nozzles applying oxidizing-gas on a' hot surface of aferrous metal body.

The invention has for its object generally the provision of an improvedprocedure and steps in a method of the character-set forth, togetherwith suitable apparatus for carrying the'same' into efiect, wherebyimproved operating'char'ac effect the desired conservation and to retainthe respect to 'the gang of nozzles on the body b eihg desurfaced; 1 a vAnother object is to provide means for apply- Y ingan"external"comp'onent'of force in a manner the puddle as a unitary mass"and to prevent its sloughing off at the sides;

Another'object is to provide an optimum range for the' angularorientations taught in the U. S. Patent to E. A. Doyle, No. 2,125,179,issued July 26, 1938, for the oxygen impinging nozzles about axesperpendicular to the surface being removed.

Still another object of the invention is to provide an arrangement ofnozzles for multiple nozzle I desurfacing adapted to give components offorce which tend to urge the reaction puddle to a central position andmaintain it there ahead of the reaction zone. v

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the several steps and the relationof one or more of such steps with respect to each of the others, and theapparatus embodying features of construction, combinations of elementsand arrangements of parts which are adapted to effect such steps, all asexemplified in the following detailed disclosure, and the scope of theinvention will be indicated in the claims.

For a fuller understanding of .the nature and objects of the inventionreference should be had to the following detailed description taken inconnection with the accompanying drawing, in

which:

Fig. 1 is-a sideelevation showing an arrangement for multiple nozzlede'surfaoing, of a billet when the top surface is being removed inaccordment used in"con nection with the illu'st tlon'in Fi 1 and depicts'the mutual inclination of the oxidizing gas streams employed inthe'ipractice of the'invention; and- 7 j Fig. 3 shows'a-modifiedarrangement of the nozzles where the number is different from that shownin Fig. 2.

In the art of desurfacingferr'ous metal bodies with oxidizing gas, it isnow common practice to remove the surface of ingots,-billets,and'thelike, to a desired relatively shallow depth in comparatively wide cuts,by impinging a plurality orrelatively voluminous side-foy-jside' streamsof oxidizing gas upon aregionof surfaee'extending'transversely to thedirection in'which' a"-cutis tofbe taken; and-at acute angles tef 'aplane which is tangent-to the surface at the points of impinge;

' merit; the'applicationof gas being'in the-general. direction of themetal removal. 'Ifhdpxidizihg' gasemployed may be either commerciallypure" oxygen era-mixture of" oxygen"and a neutral gas; the 'noz'zleexityelocity with which thegas is supplied 'is preferablyoi a relativelylowvalue. A' suitable' velocity 'ofjt'his character 'has as "its upperlimit the acoustic. velocity andmayhave, a

value taken within thegeneral range of fr'om'200 to11000 ft. per.second, as' set-'forthjin the U. S

Patent"to; Oldham,No.1951351. g

The surface removed by; the thermo-chemical reaction of the oxidizinggas" impinged upon the surface of the ferrous metal body mustbeinitially raised to the temperature at which the oxygen will react, i.e., to the oxygen ignition temperature, in order that thethermo-chemical reaction may take place. The elevating of the surface tosuch ignition temperature 'may be accomplished by the application of asuitablepreheating gas flame to the surface at a period of time and in aposition somewhat ahead of the time and region at which the oxidizinggas is applied.' A mixture of oxygen and acetylene is suitable as theheating gas mixture to be supplied in the practice of the presentinvention. Where the ingot or billet is to be desurfaced while hot, as astep in a steel mill manufacturing process, it may be unnecessary topractice the preheating of the surface to the ignition temperature sincethe uncooled billet is frequently at or above such ignition temperature.

nozzle desurfacing, the nozzles are usually so.

closely spaced that the several reaction puddles coalesce, and a singlepuddle results that moves over the surface as the desurfacing nozzlesand the metal body are removed relatively. While the puddle thus formedis a relatively viscous mass and has a'relatively high surface tension,

it has been found in practice that the puddle has as a rule has asubstantial portion in contact over a considerable area of the metalbody ahead of the gas applying nozzles, and hence imparts conductively arelatively large amount of heat to the surface to be removed. The puddlethus assists in attaining the desired preheating efiect on the surfacemetal in advance of the out.

In the practice of the presentinvention a step is taken forsupplementing the effect of the S111? face tension in the reactionpuddle in a transverse direction so as to minimize the tendency ofsloughing off at the sides and thereby accomplish a conservation of theheat of the puddle. This conservation also makes for greater uniformity"in depth of the cut which is made.

In order to carry out this step, an arrangement of nozzles is employedwhich imparts the desired assistance to the surface tension as asupplemental external force, such force being derived from the velocityof the' gas applied. To this end, a plurality of nozzles are orientedto- -ward each other through small angles about axes substantiallyperpendicular to the plane tangent to the surface being removed so as toapply transverse velocitycomponents to the surface of the puddle. ,Where more than two nozzles are employed, this is seen to involve theinclining of each pair of nozzles on opposite sides of a center linemutually toward each other. In this manner, the normal cohesive forcesof surface tension in the reaction puddle are supplemented externally sothat the puddle is retained as a unitary mass moving ahead of thereaction zone. 4

Referring now to the drawing, and particularl to Fig. 1, B denotes afragmentary portion of. a billet whose top surface is beingthermo-chemically removed by a gang of nozzles l0 arranged in accordancewith'the invention. These nozzles may be of any suitable type, forexample, of the conventional type having cylindrical bores, as nowcommonly used in the art. Here, the nozzles [0 have connections II forsupplying both oxidizing gas and heating gas to the nozzle passagesafter traversing a head [2 which may be watercooled, if desired(water-cooling connections being omitted from the drawings in theinterests of cleamess of illustration). The oxidizing gas is shown as astream i 3 impigning upon the top surface of the billet B, and making anacute angle in a vertical plane of about 25 degrees with its trace inthe tangent plane, the stream l3 being surrounded by a plurality ofsmall heating gas jets l4. The region of the surface impinged by theseveral streams of oxidizing gas is the region 01 zone where thethermo-chemical reaction takes place and burns off, as it were, thesurface metal to be removed to a desired depth, for example, to anaverage depth of inch. A puddle of slag, as indicated at P, forms aheadof the impigned gas in the reaction zone and has a billowslike crwt Rwhich moves ahead of the portion more immediately adjacent the reactionzone.

In Fig. 2, an arrangementof nozzles is shown whereby external componentsof force are applied to the surface of the puddle P to assist in itsretention centrally on the billet being desurfaced. Here, an even numberofoxidizing gas supplying nozzles are depicted and denoted respectivelyl0, l0", 1, and 10 The two inside nozzles l and |0 are seen to bemutually inclined toward the center line 2-3: of the billet at smallangles. which may have values, forexample, of from 5 to 15 degrees.- Theoutside ,nozzleslll' and iii are also mutually inclined, but atincreasingly greater angles than the inner nozzles, since in this waythe supplemental components of force may be made to have comparativelylarge values at the edge of the puddle. In practice, the nozzles Hi andHI may be inclined at angles of from 10' to 20 degrees. Any suitablemechanical spac- I ing means, for example,'a toothed bar as shown at 15,may be employed for retaining the nozzles properly .spaced -and in thedesired mutually inclined positions.

To make a desurfacing cut with the arrangement shown in .Figs. 1 and 2,preheating gas flames are first applied tothe place ,where the cut is tostart. When this place is at the oxy en ignition temperature, theoxidizing gas :streams are turned on.. After this, the billet and theheads carryingthe oxidizing gas applying noz-. zles are moved relativelyat, a suitable speed, for example, at ft. per minute. .The oxidizing gasthereby impinged upon the surface is applied not only at an acute angleto the tangent plane of the billet's surface at-the place ,ofimpingement but isinclined somewhat "laterallylthrough. angles havingaxes substantially perpendicular to the tangent plane so as to givelateral components of force thatare applied to the surface-of the-re-.

action puddle and supplement the normal c0- hesive forces operating inthe surface of the. pud-' dle producing resultants which tend to haveequilibrium only along the center line of .thebillet.

reaction .zone with little liability to substantiallosses throughsloughing off at thesides.

.In Fig. ,3, an, arrangement of-vnozzles employ-- ing an add numberiashown.- Five nozzles are.

depicted and are denoted respectively l0, Jflfilfl,

In and I0. Here, it is seen that the-central nozzle Ill is not orientedthroughany anglelabout a vertical axis but has its projection parallelto the center line :c '-a:' of the billet. The two inside nozzles In andIII are mutually inclined toward the center line through small angles aswere the nozzles I 0* and "1 in Fig. 2, while the two outside nozzles-H) and Ill are oriented through somewhat greater angles. Thus, it isseen that external components of force, increasing with the approach tothe outer edges of the reaction puddle, are provided, whichoperate toretain the reaction puddle centrally as an imperforate unitary fusedmass moving ahead of the reaction zone when a desurfacing cut is beingtaken.

Since certain changes in carrying out the above process and in theconstructions set forth, which embody the invention may be made withoutdeparting from its scope, it is intended that all matter contained inthe above description or shown in the accompanying drawing shall beinbeing applied through nozzles arranged to supply gas in relativelylarge volumes at acute angle to a plane tangent to the surface beingremoved in the region of impingement and in the general di rection of,advance of the desurfacing reaction, inclining said streams mutuallytoward each other by orientations through angles of from five to twentydegrees about axes substantially perpendicular to said tangent plane,saidorientation having a direction and magnitude such as to derivean-external component of force supplementing the normal cohesive forceswhich operate in the surface of the reaction puddle that forms in theregion impinged by said oxidizing gas streams to an extent which causesthe reaction puddle to move centrally ahead of the reaction zone withlittle liability to sloughing 05 at the sides, and imparting relativemotion to said plurality of oxidizing gas streams and said metal bdy1 2.The process of thermo-chemically desurfacing a ferrousmetal body whichcomprises applying heating gas flames to the surface to be removed toraise the temperature of the same to the oxygen ignition temperature,impinging a plurality of oxidizing gas streams upon a region extendingacross a surface of said body when at the oxygen ignition temperature,said streams being applied through nozzles arranged to supply gas inrelatively large volumes at acute angles to a plane tangent to thesurface being removed in the region of impingement and in the generaldirection of the desurfacing reaction, inclining the streams ofoxidizing gas on each side of a center line mutually toward each otherby orientations through angles about axes substantially perpendicular tosaid tangent plane, said orientations adjacent said center line beingrelatively small and. of a value from five to fifteen degrees and havinga direction such as to derive an external 'component of forcesupplementing the normal cohesive forces which operate in the surfacesof the reaction puddle that forms in the region impinged by saidoxidizing gas streams, said orientations for the streams outside ofthose immediately adjacent said center line being from ten totwenty'degrees and progressively increased whereby the transversecomponents of force tend to move the reaction puddle to the center ofthe reaction zone, there being a region of equilibrium along the centerline, and imparting relative motion of said plurality of oxidizing gasstreams and said metal body.

3. Apparatus for thermo-chemically desurfacing a ferrous metal bodycomprising, in combination, means for supporting a body in a position tobe operated upon, a group of heads movably supported above saidsupporting means, each of haid heads having a nozzle for impinging arelatively voluminous stream of oxidizing gas upon a surface to beremoved of a metal body when on said supporting means, said streamsbeing impinged at acute angles to a plane tangentto the surface beingremoved in the region of impingement and in the general direction inwhich a desurfacing reaction takes place, means for holding said headsin positions such that the streams of oxidizing gas are mutuallyinclined toward each other on opposite sides of a center line, saidinclinations being through angles of from five to twenty degrees aboutaxes substantially perpendicular to said tangent plane,- said anglesbeing selected to have directions and magnitudes which derive externalcomponents of force from the velocity of said gas streams and supplementthe normal cohesive forces operating in the surface of the reactionpuddle that forms in the region impinged by said oxidizing gas streams,and means for moving said group of heads relatively to said supportingmeans.

4. Apparatus for thermo-chemically desurfacing a .ferrous metal bodycomprising, in'combination means for supporting a body in a position tobe operated upon, a group consisting of an even numberq-of headsoperatively disposed with respect to said supporting means, each of saidheads having a nozzle for impinging a relatively voluminous streamofoxidizing gas upon a surface to be removed of a metalbody when on saidsupporting means, said streams being impinged at acute angles to a planetangent to the surface being removed in the region of impingement and inthe general direction in which a desurfacing reaction takes place, meansfor holding a pair of heads on opposite sides of a center line mutuallyinclined toward each other through angles about axes substantiallyperpendicular to said tangent plane, said angles having a magnitude offrom 5 to degrees and directions such as to give external components offorce derived from the velocity of said gas streams which supplement thenormal cohesive forces operating in the surface of the reaction puddlethat forms in the region impinged by said oxidizing gas streams, a pairof nozzles which are outside of said first-named pair and on oppositesides of said center line being mutually inclined toward each otherthrough angles of slightly greater magnitude than said first-namedangles, and means for moving said group of heads relatively to saidsupporting means.

5. Apparatus for thermo-chemically desurfacing a. ferrous metal bodycomprising, in combination, means for supporting a body in a position tobe operated upon, a group consisting of an odd number of headsoperatively disposed with respect to said supporting means, each of saidheads having a nozzle for impinging a relatively voluminous stream ofoxidizing gas upon a surface to be removed of a metal body when on saidsupporting means, said streams impinging at acute angles to a planetangent to the surface being removed in the region of impingement and inthe direction in which a desurfacing reaction takes place, means forholding the central head in said group in a position such that theprojection of the streamof oxidizing gas impinged on the surface to beremoved is parallel to the center line of said group, the pair of headsadjacent said central head being inclined toward each other throughangles whose axes are substantially perpendicular to said tangent plane,said angles having a magnitude of from 5 to 15 degrees and a directionsuch as to give a component of force derived from the velocity of saidgas streams operating inwardly toward said center line, the pair ofheads next adjacent said first-named pair of heads being inwardlyinclined through angles about axes substantially perpendicular to saidtangent plane and havingmagnitudes of from 10 to degrees and directionssuch as to give external components of force directed toward said centerline, and means for moving said group of heads relatively to saidsupporting means.

JAMES HAROLD BUCKNAM.

CERTIFICATE OF CORRECTION.

P en n 2,151 095 m y 9,, 195.9.

JAMES-HAROLD BUCKNAMQ" It 5 5 her certified that error a ear in theprintedepecifieation of theiabove numbered patent. requiring correctionas follows: Page 2, "first cplimzh; line fih fif jfimpignirig" readimpinging; line 65-66, foi "impighed" read. impinged} eame page, secendcolumn -fline 1 5', for the word "add read, odd; page first c m line 2,claim l, for 16" read angles; line 59', f0; "ha-id read said; and thatthe said Letters Patent should be read with this; corfec tion thereinthet the same may confoi'm to the reco rd of the case inthe PatentOffice. v

Signed and sealed this 15th day of June A. D. 19 9.

Henry Van Arsdale (869.1) Acting Commissioner of Patents.

